Numerous different types of reel-type gaming machines have been developed to provide desirable game features and play characteristics in these types of wagering games. As used in this disclosure and the accompanying claims, a reel-type gaming machine comprises a gaming machine in which at least some results are displayed to the player in the form of an array of game symbols, where each game symbol is displayed on the periphery of a spinnable reel, either a physical reel or a video simulation of such a reel. For example, a reel-type gaming machine may include a display system with five adjacent reels (either physical reels or video simulations) all aligned along a horizontal axis of rotation, with each reel showing a line of three or more game symbols in the array of symbols. Other reel-type gaming machines may show only a single symbol on each physical or simulated reel and include a separate physical or simulated reel for each symbol location in the array of game symbols used to display results. In all of these reel-type gaming machines, winning results are shown at least partially by the particular pattern or patterns of game symbols appearing in the array of game symbols for a given play of the game.
Some reel-type games include wild symbols in the set of game symbols used to populate the array of game symbols for a given play of the game. A wild symbol is a symbol which has the property that it may represent any one of a number of different game symbols as necessary to make a winning combination of game symbols. For example, a reel-type game may include a pay table which defines a number of different prize levels in terms of combinations of game symbols aligned along a pay line of game symbols through the array of game symbols. In this example, a prize may be awarded when the array of game symbols produced for a play of the game shows three “X” game symbols aligned along a pay line defined for the game. If an array of game symbols produced for a play of the game shows two “X” game symbols and one wild symbol aligned along the pay line, the wild symbol will count as an “X” game symbol to make a winning combination of three “X” symbols along that pay line. Because pay lines may be non-linear and different pay lines may cross at a given game symbol in the array of game symbols produced for a play of the game, it is possible for a wild symbol to represent multiple different game symbols in the same play of the game.
Although wild symbols are commonly used in reel-type games, wild symbols can frustrate a player in certain situations. In particular, in view of their ability to assist in producing winning game symbol combinations, wild symbols carry with them a certain degree of expectation that they will in fact produce winning combinations. If wild symbols routinely appear in the various arrays of game symbols produced over the course of a number of plays in a reel-type game, but happen to be positioned in the array so that they do not contribute to a winning combination, the perceived value of the wild symbol may be reduced and the player may become frustrated at seeing the wild symbols appear for a play only to find that they are in the wrong position to contribute to a winning combination of game symbols.